#include "include/geom.h"

Tri* alltris[512];
size_t allsize = 0;

Tri* tri_init(Pt a, Pt b, Pt c) {
    Tri* tri = malloc(sizeof(Tri));
    *(alltris + allsize) = tri;
    allsize++;
    *tri = (Tri){a, b, c};
    return tri;
}

bool tri_within(Pt pt, Tri* tri) {
    double denom =
        ((tri->b.y - tri->c.y) * (tri->a.x - tri->c.x) +
         (tri->c.x - tri->b.x) * (tri->a.y - tri->c.y));
    double a = ((tri->b.y - tri->c.y) * (pt.x - tri->c.x) +
                (tri->c.x - tri->b.x) * (pt.y - tri->c.y)) /
               denom;
    double b = ((tri->c.y - tri->a.y) * (pt.x - tri->c.x) +
                (tri->a.x - tri->c.x) * (pt.y - tri->c.y)) /
               denom;
    double c = 1 - a - b;
    return 0 <= a && a <= 1 && 0 <= b && b <= 1 && 0 <= c && c <= 1;
}